(CNN) -- North Korea, in a statement identical to one issued two years, says it has finished extracting 8,000 fuel rods from its reactor at Yongbyon, which it shut down a month ago, according to a report on its official news agency.

That step would allow the North Koreans to reprocess the spent fuel into weapons-grade plutonium -- after the rods are cooled, a process that could take two to three months -- but Wednesday's Korean Central News Agency report does not indicate whether they are preparing to do so.

North Korea is "taking necessary measures to bolster its nuclear arsenal for the defensive purpose of coping with the prevailing situation, with a main emphasis on developing the self-reliant nuclear power industry," the report quoted a foreign ministry spokesman as saying.

The North Koreans have previously claimed to have extracted the rods and reprocessed the fuel into plutonium, accounting for the five to six nuclear weapons the United States and the International Atomic Energy Agency believe the country already has.

U.S. officials said that the statement was a re-release of an identical statement made two years ago. The officials ventured no opinion on why the North Koreans would re-release the previous statement.

Asked if the United States believed the North Korean statement, White House spokesman Scott McClellan said, "North Korea's provocative comments only isolate it further from the rest of the international community. We would hope that North Korea would return to the six-party talks soon."

He repeated the answer when asked a second time.

Nuclear experts say the extracted fuel rods could provide enough plutonium for three to four more.

The country announced in February that it had nuclear weapons, saying it would not take part in another round of six-party disarmament talks because of U.S. hostility towards its government.

China on Wednesday urged restraint from all parties to six-way talks. "We ask all the parties to exercise restraint and we hope that they will do nothing that is detrimental to the resumption of the six-party talks," Foreign Ministry spokesman Liu Jianchao told Reuters.

A U.S. Defense Department official said that recent satellite images indicate the North may be preparing for a nuclear weapons test -- a prospect that IAEA chief Mohammed ElBaradei chief said could open "a Pandora's box" with "disastrous political repercussions." (Full story)

But, he told CNN's Wolf Blitzer Sunday, the agency has received no satellite information and "cannot do very much as an international institution right now on this issue other than to express concern."

The same Defense Department official also said that the activity seen on the satellite imagery may be designed to mislead.

North Korea did test a conventional short-range missile, firing it into the Sea of Japan on May 1.

North Korea withdrew from its nuclear agreements in 2002 and restarted Yongbyon, which it had shut down in 1994. It kicked out U.N. inspectors and monitors as well.

"The DPRK had already declared in December 2002 that it would re-operate the above-said plant and resume the construction of two other nuclear plants, one with a capacity of 50,000 kw and the other with a capacity of 200,000 kw which had been frozen according to the DPRK-U.S. Agreed Framework -- the keynote of which is the provision of light-water reactors to the DPRK -- because the Bush administration threatened the DPRK with nuclear weapons in violation of the AF," a foreign ministry spokesman told the state news agency.

DPRK is short for the formal name of the country, the Democratic People's Republic of Korea.

North Korea agreed to six-party talks with the United States, Russia, China, South Korea and Japan, but opted out of those talks in September 2004, citing a 'hostile" U.S. policy toward it.

Then, in February, Pyongyang declared it had nuclear weapons and would continue its boycott of talks indefinitely unless Washington agreed to one-on-one talks. The Bush administration has refused, arguing that the issue affects the entire region and therefore the other parties should be included.

In March, the United States threatened to take the matter to the United Nations Security Council, and in the past two weeks, both sides have traded insults with North Korean leader Kim Jong Il calling President Bush and his advisors "hooligans" and Bush labeling Kim "a tyrant."